This invention is concerned with filtration of noxious odors and components out of gases such as given off by a sewage treatment facility. More specifically, the invention concerns a modular support system as described in U.S. Pat. No. 7,713,732, providing a raised biofiltration support bed, and including bridge modules that connect with the assembly of floor tile modules to provide a continuous floor, spanning across a trench through which air or gas is supplied.
Biological air pollution control has been used on an increasing basis in recent years to cleanse noxious and odorous gases, such as those emanating from a sewage treatment plant. Statutes mandate that those noxious/odorous gases be contained. The biological filtration systems or biofilters utilize a bed of stacked biofilter material such as compost, tree bark, peat, heather or soil, generally several feet deep. The containment gas from the sewage treatment plant or other sources is blown through the biofilter material in an upward direction. The material in the biofiltration bed provides an environment for a diverse culture of microorganisms, which can be seeded into the medium and which degrade the gaseous pollutants as they pass through the biofilter.
U.S. Pat. No. 7,713,732 describes a system of interlocking modular floor tiles with support legs that raise the floor above a hard surface below (such as concrete) providing a plenum below the modular floor through which air or gas is distributed. Earlier U.S. Pat. Nos. 7,422,895 and 6,255,102 also are concerned with such systems, all three of these patents being owned by the assignee of the current invention and all three being incorporated herein by reference in their entireties.
In many biofiltration systems in recent years, the air or gas (herein referred to as air) has been delivered not from an above-floor inlet tube or conduit such as shown in the above-referenced patents, but through an underfloor duct. In some instances this can take the form of a linear trench (with or without a pipe) formed in the concrete surface below the modular floor, or several such trenches parallel to one another. The trench creates a problem with continuity of the perforated floor system. Trenches can be 24 inches, 30 inches, 36 inches or even 48 inches in width. This requires an interruption in the modular, interconnected floor tile system and requires some form of structure to bridge across the trench and establish continuity and integrity for the filter bed floor structure.
The continuity problem has been addressed in some biofiltration bed systems with stainless steel bridging elements, which corrode in a short period of time due to the corrosive nature of the gases. Molded plastic bridging elements have been used as well, but not with adequate strength and durability and without interconnection to the biofiltration bed sections on each side of the trench, thus not providing adequate integrity of the raised floor system.
Accordingly, it is a primary objective of the invention to improve the integrity of a modular support system for biofiltration or for compost materials, with the support system including bridging modules spanning over one or more air delivery trenches, without compromising the integrity of the system.